1. Field of the Invention
Aspects of the present invention relate to a roller for an image forming apparatus such as a printer, a copy machine, and a facsimile. More particularly, aspects of the present invention relates to a roller device for an image forming apparatus that is capable of precisely controlling the position of a roller.
2. Description of the Related Art
Image forming apparatuses generally comprise a photoconductive medium, a developing roller, a developer supplying roller, an agitator, a cleaning roller, a developer controlling blade, and a cleaning blade. Rotary rollers such as the photoconductive medium, the developing roller, the developer supplying roller and the agitator are rotated according to a predetermined velocity and direction by a driving force transmitted through a predetermined gear train. In an image forming apparatus, control of the position of rollers is a significant matter since the positioning of rollers in a frame can greatly affect the image forming operation.
As shown in FIG. 1, which shows a generic image forming apparatus, rollers 1, 2 and 3 are position-regulated by being supported by a side frame 4. Reference numeral 5 of FIG. 1 denotes a main frame of the image forming apparatus. FIG. 2 shows an example of a conventional roller device for the image forming apparatus.
As shown in FIG. 2, the roller device in the generic image forming apparatus comprises a rotary roller 10 having a shaft 10a, a driving gear 11 connected to the shaft 10a for power transmission, and bushings 12 and 12′ that respectively fit onto opposite ends of the shaft 10a. The roller device is mounted to a predetermined location of the side frame 4 using the bushings 12 and 12′.
Since the roller 10 is connected to the side frame 4 through the bushings 12 and 12′ as described above, the roller 10 could be mis-aligned due to assembly tolerance or geometric tolerance. When the roller 10 is wrongly aligned, especially when the bushings 12 and 12′ are wrongly aligned, defects in the image forming process, such as void spots in the image at regular intervals (white void), unevenness in the horizontal density of the image, unevenness in the development and transfer of image-forming material to the image, and inferior application of the developer, may be caused. As a result, the image quality can be considerably degraded.